Thermostatic control device



April 1952 J. H. HURLBUT ETAL 2,592,424

THERMOSTATIC CONTROL DEVICE Original Filed Jan. 14, 1946 3 Sheets-Sheet l mags H ea 5w;

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April 1952 J. H. HURLBUT ET AL 2,592,424

THERMOSTATIC CONTROL DEVICE Original Filed Jan. 14, 1946 5 SheetsSheet 2 lib/W55 H. HUQLEUE CHME$QHWWNGEQ INVENTORS.

P 8, 1952 J. H. HURLBUT ET AL 2,592,424.-

THERMOSTATIC CONTROL DEVI CE Original Filed Jan. 14, 1946 5 Sheets-Sheet I5 IO 26 6 '1 V I 1 M mi/1551 1 Hue/.507;

Arrow/M Patented Apr. 8, 1952 'THERMOSTATIC CONTROL DEVICE James H. Hurlbut, South Gate, and Charles R.

lieiningenStockton, Calif., ass'ignors to Robertshaw-Fulton Controls Company, Greensburg, Pa.,-a c011poration of Delaware Original applicationdanuary 14, 1946,.SeriaLN0. 641,037. Divided and this application January 26, "1950,. SerialiNo.140,728

3 Claims.

This invention relates to controls for fluidiuel burners and more particularly to thermostatic control devices for regulating the flow of fuel to the burners by means of a valve movable between controlling positions with a snap-action. This application is a division ofourcopendingapplication, Serial No. 641,037, filed January 14, 1946, now Patent No. .2,584 458,dated Februaryfi, 1952.

It is a principal object ofthis invention to effect adjustment of thetemperature to which the valve will respond by means "operable exteriorly of the device while precluding the possibility of fuel leakage therefrom.

Another object of this invention is to effect adjustment of a snap-action mechanism disposed within a valve casing by means operable exteriorly of thecasing and separated from the-snap-action mechanism by an imperforate seal to thereby set the temperature at which the valve will be actuated.

A preferred form of this invention has a snapaction mechanism with a-movable fulcrum member disposed within a valve casingwhich is provided with a port closed'bya fiexiblediaphragm. ihe fulcrum member is operatively engageable with one side of the diaphragm and adjusting means is operatively engageable with the other side of the diaphragm to :set the position of the fulcrum member and thereby-set the temperature at which .the valve will be actuated.

In the drawings:

Figure .1 is a side elevational view of the device including a fragment of a thermostat elementin section.

Figure 21s a front'elevational view.

Figure 3 is a longitudinal, sectional view taken on the line 3-3 of FigureLZ.

Figure 4 is a cross-sectional-viewtaken on the line 4-4 of Figure 6.

Figure 5 is a cross-sectional view taken on the line 5-5 of Figure 3.

Figure fi is a side view-of the'device with aportion of the casing broken awayshowing the :interior construction.

Referring to the drawings, the invention is 4 shown as being embodied in a combination thermostat and automatic pilot control device. The device is incorporated in a single casing identified generally by the character 10 which consists of a body H defining the several chambers, the top of which isclosed bya cap orbonnet 12 attached by screws l3 which draw the cap against a suitable gasket 14 in order toseal the connection between the capand the body. At the rear of the casing is a threaded fitting l5 by means of which the casing may be attached to an appropriate gas heated appliance, the fitting providing a-means-by which a temperature sensing unit Hi may be extended from the easing into the appliance.

On the front of the casing is provided ahandle 1'1 'for controlling the flow of gas into thecasing. The handle may, asindicated, be set at either "off" position, pilot position or on position, the latter positionpermitting gas to flowboth to a-pilot light and a main burner located within the appliance. Also, on the fronto'f the casing is-provided an adjusting knob or'wheel 48 hearing suitable indicia and adapted to be rotated for adjusting the thermostat assembly member in order to maintain-either a hot-condition, a normal condi- 'tion, or a relatively cold condition in the gas heated appliance.

When the device is in operating condition, gas will flow into the casing, through various chambers and valve ports within the casing wherein it is subject to safety-and thermostatic control, and thence outwardly from the casing either to a gas line supplying the main burner or to a gas line supplying the pilot burn'er or to both. In-order to simplify this description, the gas lines and burners have been-omitted but maybe considered as being'located within any appliance to which the device may be attached.

The :casing is provided with an inlet port 19 located at the "left side-of the body, as shown in Figure 14, through'which-gas passes from a supply line to a primaryichamber-ZU. "Gas follows apath through the various interior portions of the casing defined successively by the primarychamber 20, an internal valved :port 2!, a secondary dispersion chamber 22 (see Figure 3) thence through the interior of .a plug valve member 23, from which it travels through .a valved passage 24 past .a control port 2.5 into a distributing chamber 26. At :the bottom'of the distributing chamber is an outlet port 2'! (Figure 6) which is adapted to be connected-to a gas line supplying the'main burner of any appliance with which the unit control may be used. Also, connected 'to the plug valvemember is a pilotpassage 28 (Figure 4) which is connected to a pilot outlet 25! in turn adapted to'be attached -to a gas linesupplying a pilot light installed in the same appliance.

In initial position .gas is prevented from flowing through the control device by reason'o'f the fact that a safety valve element 33 is pushed to a closed position by a coiled spring 34 located beneath the valve and tending to press the valve upwardly to seat against the lower side of the internal valved port. Inorder to open the safety valve, there is provided a stem 35 having a limited sliding attachment to the safety valve element. The stem extends outwardly through a packing nut 36 to the exterior of the casing. The packing nut is provided with a pocket 31 within which is positioned a push button 38 attached to the outside end of the valve stem and normally lifted to a distended position by a coiled spring 39. A sealed friction packing 40 is provided at the inside end of the pocket so that gas will not leak past the stem.

To add to the seal Where the stem passes through the casing there is provided a sealing disk 41 having a soft face 42 designed to be pressed against an annular rim 43 surrounding the aperture in the lower end of the packing nut. The sealing disk is normally seated upon the annular rim except for a brief moment while the pilot light is being lit.

A thermo-electric magnetic means is provided for holding the safety valve in open position. This device consists of a magnetic coil of somewhat conventional design housed within a fitting 46 which is located beneath the casing and extends threadedly into the primary chamber 20. Within the fitting is located the electro-magnetic coil, of standard construction, operable to attract and hold the safety valve element constructed of a suitable metal. For supplying electric current to the electro-magnetic coil there is provided a thermo-couple 41, likewise of previously known construction, and consisting of an outer tube 48 of one kind of metal housing therein and a rod 49 of another kind of metal joined at a point 50 which is adapted to be located near the pilot flame. The thermo-couple is of such construction that when heated an electric current is generated which energizes the electro-magnetic coil in turn attracting and holding the safety valve element.

To set the control device so that the safety valve is opened, the push button 38 is pressed downwardly which in turn through the stem 35 depresses the safety valve against spring pressure to the position shown in Figures 3, 4 and 5.

The control device is so arranged that seta ting of the safety valve element 33 is prevented except when the handle I1 and plug valve member are turned to pilot position. In other positions of the handle l'l, namely, off and on positions, it is not possible to depress control button 38 to permit flow of gas through either the main burner or the pilot burner.

While the safety valve is being held down, the pilot flame is lit and permitted to burn until the thermo-couple is heated a sufficient amount.

When heating has reached a certain point, sufficient electricity will be generated to energize the electro-magnetic coil which will hold the safety valve element against it, in open position. As soon as this has occurred, pressure on the push button may be released, and the coiled spring 39 will elevate the push button together with the stem which is permitted to slide upwardly relative to the safety valve element. The stem will move upwardly until the sealing disk finds its position against the annular rim 43. The safety valve will then remain open until something occurs to extinguish the pilot light and permit the thermo-couple to cool. Upon cooling, the supply of electric energy is cut off and the electro-magnetic coil becomes de-energized releasing the safety valve element which is then pressed upwardly to closed position.

For controlling the flow of gas which passes from the primary chamber through the open valved port 2| into the secondary dispersion chamber for distribution to the burners, there is provided a manual control incorporated in the plug valve 23 which is manipulated by the handle I]. As indicated in Figure 2, the handle has three positions, namely, an off position, a pilot position and an on position wherein gas is supplied to both the pilot and the main burner. The handle is shown in pilot position in Figure 2 wherein the point marked Pilot is turned to a position opposite a position marker 5|. Pilot position of the plug valve member is also illustrated in Figure 4.

The plug valve member shown in Figure 3 is provided with a valve stem 52 having a hollow threaded interior 53 and extending outwardly through a packing gland 54 attached to the casing. Within the packing gland is a coiled spring 55 retained in a suitable recess and adapted to press the plug valve element inwardly into seating position. The handle I! is non-rotatably attached to the outside end of the valve stem.

As indicated in Figures 3 and 4, the plug valve member is provided with an axial interior passage 56 having a lateral outlet port 51 which communicates between the interior passage and one or another, or both, of passages 24 and 28. On the exterior of the plug valve member is a slot 58 communicating with the outlet port in such a manner that when the lateral outlet port is directed toward the valved passage 24 gas may also pass through the slot to the pilot passage 28.

For controlling the rate of flow of gas to the main burner through the valved passage 24, in the event gas pressure might be changed for one reason or another, there is provided an adjusting plug 59 which has its position within the axial interior passage 56. 'The adjusting plug has a beveled end so that a gradual, carefully controlled adjustment may be made as the plug is moved to one of several positions partially closing the lateral outlet port. In order to change the adjustment, the plug is provided with a threaded stem 60 engaging the threads within the plug valve stem. A screw driver slot is provided in the stem 60, and access is gained by removal of a cap screw 6| at the outside end of the plug valve stem. After the adjustment is completed, the cap screw is replaced and screwed tight so that the hollow interior of the plug valve stem is sealed against possible escape'of gas.

For controlling the flow of gas into the control chamber 26 and thence outwardly to the main burner there is provided a control valve member which is adapted to cooperate with the temperature sensing unit [6 through a snap action mechanism 66. Details of a satisfactory type of snap action mechanism will be found illustrated and explained in Patent No. 2,238,837.

The control valve element is normally urged downwardly to a closed position by means of a coiled spring 61 retained by a suitable spring keeper (not shown) formed integral with a cap 69, the cap having a sealed position with respect to the casing and in particular to the bonnet l2. The valve element has a stem 10 slidably positioned within a suitable bore inside the spring keeper and is provided with a threaded extension H by means of which action of the valve may be adjusted. The valve is adapted to seat upon an annular valve seat 12 surrounding a control valve port 13.

For lifting the control valve from its seat to open position and subsequently permitting it to close, the temperature sensing unit operates through the snap i-action mechanism which in turn is connected 'to a'bell crank lever "M pivoted at and engaging the threaded extension H.

The temperature sensing unit 16 comprises a tubular member 16 within which is positioned the customary invar rod 18, in this instance fixed in location with respect to the tube by providing the rod with a tight fit within a sealed plug 79.

The rod is provided with a suitablesnap action mechanism I06 operable through a bell crank lever M to manipulate the control valve.

A diaphragm Hi8 makesagas tight sealacross a control port 109 and is held in place ancl sealed at its perimeter by a threaded plug H0. The diaphragm may be a thin, metallicelement which is permitted a certain freedom of movement at the center in a lateral direction to make .possible an adjustment of the snap action mechanism.

For supporting and centering the snap action mechanism there is provided a'disk Ill which is mounted for sliding movement along the wall of the passage which-opens into the control port. The disk is fixed to a collar I H which is equipped with a fulcrum Ill bearing upon a snap disk H2. The collar is adaptedto move against the disk thereby to alter the adjustment of the snap action mechanism. Upon the rod 18 is afiixed a collar 80 and adjacent thereto is a second collar H3 which is moved by the rod and attached collar 88. The collar H3 is provided with a fulcrum I IS, the point of action of which is opposed and laterally-spaced from the point of action of the fulcrum :l l l. MI is moved relative to the collar M3, the setting of the snap action mechanism is changed.

For moving'the collar 11! there is provided a center pin l [4 on the side ofthe diaphragm opposite from the .collar 1 I l, the center pin being adapted to be received within a cup-like recess in the inside end of an adjusting pin H6. The adjusting pin in turn is fixed in position on a handle wheel [-8 by means of a set screw 92'.

The adjusting pin has a threaded engagement 4 with the threaded plug H 0.

Therefore, when the adjusting pin is rotated by means of the handle wheel, it will shift its position endwise, and when moved inwardly will press the adjusting pin against the diaphragm. This motion will shift the position of the center of the diaphragm inwardly and be translated to the collar Ill pressing the collar inwardly and thus changed the setting of the snap action mechanism. When the adjusting pin is moved in an opposite direction, the setting of the snap action mechanism will undergo a change in the opposite direction by reason of tension inherent within the mechanism itself.

In operation of the device the handle wheel or knob ill will customarily be set at normal position wherein a dot 93 thereon will be positioned opposite the position marker 5! or in cold position if preferred. Since the temperature sensing unit is cold at this stage, in either position the control valve will ordinarily open, thereby permitting a potential flow of gas outwardly through the main burner outlet port.

To ignite the pilot light in the appliance it is necessary to turn the handle I! to pilot position and then depress the button 38 to push the safety valve 33 to open position against or near the electro-magnetio coil. In pilot position the plug valve will be rotated to the position shown in Figure 4 where it will be apparent that gas may When the collar l 6 flow fromtheidispersion chamber22 through the axial passage 56 of the plug valve member,- thence'outwardly through the'lateral port 51 to the pilot passage 28 and pilot. outlet port'25. The pilot burner may then be lit, and heat generated will be transformed intoelectricit-y by means of the thermo-couple 4"! and hold the safety valve in open position, whereby gas flowing .into the device through the inlet port will be available to be passed through the device depending upon how other controlling-valves :areset.

Asilong as the'handle 11 remains :in pilotposition, no gas can-flow to the main burner outlet port. Howevenafter the pilot has been-ignited, the handle may be turned to :full on position, and gas will then be permitted to pass through the plug valve member through both the valved passage 24 and the pilotpassage 28. The-pilot outlet port will continue to be supplied, and gaswillalso be available for the main :burner. Since in normal position of'the wheel or knob l8 the control valve will be open, gas will immediately pass into the control chamber 26 and thence outwardly through the outlet port to the main burner which in turn may be ignited by the pilot.

As the appliance heats up the temperature sensing unit will be heated, and when a sufiicient temperature has been reached, the snap action control I06 Will be 'operatedto release the control valve member 65 to aspring pressed closed position, thereby shutting oif flow of gas to the main burner. Later, as the appliance cools off, the temperature sensing unit will again function in an opposite direction causing actuation of the snap action mechanism in ;a contrary direction to open the controlvalve member causing gas to again flow through themain burner outlet port. Meanwhile, the thermostat actionmay be-altered by rotation of the wheel 4'8 in :one :direction or another.

If the handle 'i'! should then be turned to full oil position, gas flow to both .thegpilotoutlet port and the main burner outlet port would be shut off. As soon as the pilot ceases to burn, the thermo-couple A! cools, acting through the velectromagnetic coil to release the safety valve to a closed position. The pilot cannot again be ignited by any means until the handle I! is rotated to pilot position.

If instead of turning the handle I! to oiT position the pilot flame were inadvertently put out while the handle is turned to full on position, the

thermo-couple upon cooling would interrupt energization of the electro-magnetic coil and in this instance also release the safety valve, permitting it to close and shut oif the entire gas supply to both pilot and main burner outlet ports. Cooling takes place with sufiicient promptness so that no appreciable quantity of unignited gas will escape. In this instance likewise the device cannot again be put into operation until the handle I1 is again rotated to pilot position.

By provision of a unitary control of the type described incorporating in cooperable relationship in one casing a thermostat control, a safety control, and necessary main burner and pilot adjustments, there is provided a unitary control device which can be conveniently located on a gas-fired appliance wherein all controls for handling the flow of gas may be tightly sealed and made easily accessible. Full control being thereby localized, problems of adjustment and servicing are minimized. By placing all controls within a single unit, all adjustments may be readily made in the shop before the unit is incorporated into an appliance. Adjustments are, however, made readily accessible. Should conditions change in the field, settings may be varied in order to accommodate the device to the changed conditions. The device is positive in its action and effective of maximum safety regulation in that the gas supply is completely shut off whenever the pilot light is extinguished and cannot be renewed except under conditions of maximum safety.

Although the invention is herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

We claim:

1. In a thermostatic control device, the combination of a casing having a control port formed therein, a flexible diaphragm closing said port, valve means for controlling fluid flow through said casing, thermally responsive means including an operating member disposed within said casing to be movable relative thereto, snap-action means for transmitting movement from said operating member to said valve means, said snapaction means including a thrust element mounted on said operating member for movement therewith, and an adjustable fulcrum element operatively engageable with one side of said diaphragm, and adjusting means operatively engageable with the other side of said diaphragm for adjusting the position of said fulcrum element relative to said thrust element to thereby set the temperature at which said snap-action mechanism will actuate said valve means.

2. In a thermostatic control device, the combination of a casing having a control port formed therein, a flexible diaphragm closing said port, valve means for controlling fluid flow through said casing, a temperature sensing device including an elongated rod extending into said casing, a snap-action device for transmitting movement from said rod to said valve means,

said snap-action device including a thrust element operatively connected to said rod for movement therewith, and a fulcrum element movable relative to said rod and operatively engageable with one side of said diaphragm, and adjusting means operatively engageable with the other side of said diaphragm for adjusting the position of said fulcrum element relative to said thrust element to thereby set the temperature at which said snap-action mechanism will actuate said valve means.

3. In a thermostatic control device, the combination of a casing having a control port formed therein, a flexible diaphragm closing said port, valve means for controlling fluid flow through said casing, a temperature sensing device including an elongated rod extending into said casing, a snap-action device within said casing for transmitting movement from said rod to said valve means, said snap-action device including an annular snap disk, an annular thrust element cooperable with said disk and mounted on said rod for movement therewith, and an annular fulcrum element cooperable with said snap disk and slidably mounted for axial movement relative to said rod, said fulcrum element being operative- 1y engageable with one side of said diaphragm, and adjusting means operatively engageable with the other side of said diaphragm for adjusting the position of said fulcrum element relative to said thrust element to thereby set the temperature at which said snap-action device will actuate said valve means.

JAMES H. HURLBUT. CHARLES R. HEININGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

